Electric actuator

ABSTRACT

An actuator is disclosed, which comprises a drive motor, a rotary member to be rotated by the drive motor, and a plunger for reciprocating in its axial direction. The plunger has a first and second guide portions formed thereon. The actuator further comprises a guiding member held in the rotary member. The guiding member includes a first spiral guide surface for guiding the first guide portion therealong to move the plunger in a direction to protrude it, a second spiral guide surface for guiding the second guide portion therealong to move the plunger in a direction to retract it, a first position regulating surface for regulating the retraction of the plunger when it contacts with the first guide portion, and a second position regulating surface for regulating the protrusion of the plunger when it contacts with the second guide portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric actuator and, moreparticularly, to an electric actuator equipped with a retractableplunger that can protrude from and retract into the body of theactuator.

2. Description of the Related Art

As is generally the case, the conventional motorized vehicle 100, asshown in FIG. 1, has a door 101 equipped with a locking device 102. Thislocking device 102 locks the door 101 in a closed position. A doorhandle 103, attached to the inner panel of the door 101, allows thevehicle's operator to both open and lock the door 101 by disengaging andengaging the locking device 102. It is also generally the case that thelocking device 102 comes equipped with a locking mechanism to preventthe locking device 102 from being operated despite the operation of thedoor handle 103. A knob 106, connected to the locking mechanism by alever 105, allows the vehicle's operator to engage or disengage thelocking mechanism. When the knob 106 is pulled up or down, the lockingmechanism in the locking device 102 can be operated through the lever105. When the knob 106 is lowered, the locking device 102 engages thelocking mechanism in a locked state to prevent the door from openingeven if the door handle 103 is manipulated. When the knob 106 is raisedfrom a lowered position, the locking mechanism is disengaging allowingthe door to be opened by operation of the door handle 103.

An electric actuator 107 is incorporated inside the door 101, andconnects to the locking device 102 via the lever 105. As shown in FIG.2, the electric actuator 107 is coupled to a safe lock switch 109 and avehicle speed sensor 110 via an electric control unit (i.e., ECU) 108provided with the vehicle 100. The safe lock switch 109, disposed in thedoor 101, and the vehicle speed sensor 110 are electrically coupled withthe locking device 102.

When the vehicle 100 is operated at a predetermined speed with unlockeddoors (i.e., in the unlock state of the locking device 102), the ECU 108operates the electric actuator 107 in response to a signal generated bythe vehicle speed sensor 110. In such a case, the electric actuator 107causes knob 106 to be placed in a lowered or depressed position. Theactuator 107 thus causes the locking mechanism to secure the door 101 ina locked state. In other words, the electric actuator 107 pulls down theknob 106 and actuates the locking mechanism in the locking device 102through the lever 105. Thus, the locking device 102 comes into the lockstate in which the door 101 cannot be opened even if the door handle 103is operated.

When the safe lock switch 109 is operated by a vehicle's operator, withthe device 102 in the lock state, for the purpose of opening the door,the ECU 108 operates the electric actuator 107 to pull up the knob 106and brings the locking device 102 into the unlock state, in which thedoor 101 can be opened if the door handle 103 is operated. On the otherhand, when the safe lock switch 109 is operated by the vehicle'soperator with the device 102 in the unlock state, the ECU 108 operatesthe electric actuator 107 and actuates the locking mechanism in thelocking device 102 through the lever 105. Thus, the locking mechanism isforcibly operated independently of the vehicle speed to establish thelock state, in which the door 100 cannot be opened even if the doorhandle 103 is operated.

In addition to the above operation, the locking mechanism can also bemanually operated by a vehicle passenger by physically manipulating theknob 106 up or down to respectively lock or unlock the door 101 (i.e.,to bring the locking mechanism into the lock state or unlock state).

An Examined Japanese Patent Publication No. 3-25590 discloses atraditional electric actuator for switching the locking device 102between the lock state and unlock state. This electric actuatorcomprises a rotary disc having a cam groove and a cam follower leverprovided with a cylindrical cam follower. As the rotary disc is rotatedclockwise by a drive motor, the cam follower slides along the cam grooveof the rotary disc. When the cam follower comes into contact with afirst abutting portion formed in the cam groove to define a lockingposition, the rotation of the rotary disc is regulated. Then, the camfollower lever operates the locking device to bring the door into thelock state. On the other hand, when the rotary disc is rotatedcounter-clockwise, this causes the cam follower to contact with a secondabutting portion formed in the cam groove to define an unlockingposition. Consequently, its rotation is regulated, and the cam followerlever operates the locking device to bring the door into the unlockstate.

The cam follower lever in the conventional actuator, however, utilizesonly one cam follower. Each time the single cam follower slides alongthe cam groove, it comes into collision against the inner walls of thecam groove at the first and second abutting portions. In addition, thecam follower is always in sliding contact with the cam groove. As aresult, the cam follower is subject to being seriously worn.

Moreover, since the cam follower is formed with a cylindrical shape, theabutment between the follower and the first or second abutting portionsin the cam groove results in line-contact. As a result, an impact isalways applied to specific portions of the cam follower, lowering thedurability of the cam follower. These types of actuators also requirerelatively large numbers of component parts. This makes theirmanufacture and assembly relatively complex and difficult.

In the conventional actuator, moreover, a force may be applied to anengaging projection of a lock lever through a fork member connected tothe knob, when the actuator is manually operated. At this time, the camfollower lever is turned by an intermediate lever connecting the camfollower lever with a lock lever. As the cam follower lever is turned,the cam follower linearly moves along a linear groove joining the firstabutting portion with the second abutting portion. Unless the camfollower is disposed in the linear joining groove, however, the lockingdevice cannot be manually operated in response to the manual operationof the knob.

SUMMARY OF THE INVENTION

Accordingly, it is a primary objective of the present invention toprovide an electric actuator which has an excellent durability and whichis capable of reliably engaging the locking device when manuallyoperated.

It is further object of the present invention to provide an electricactuator that requires a relatively small number of component parts soas to facilitate its assembly.

To achieve the foregoing and other objects and in accordance with thepurpose of the present invention, an improved actuator is provided.

The first type of the actuator according to the present inventioncomprises a drive motor, a rotary member to be rotated clockwise andcounter-clockwise by the drive motor, and a plunger for reciprocating inits axial direction, a portion of which protrudes outside the actuator.The plunger has a first and second guide portions formed thereon. Theactuator further comprises a guiding member held in the rotary member.The guiding member includes a first spiral guide surface for guiding thefirst guide portion therealong to move the plunger in a direction toprotrude it, a second spiral guide surface for guiding the second guideportion therealong to move the plunger in a direction to retract it, afirst position regulating surface for regulating the retraction of theplunger when it contacts with the first guide portion, and

a second position regulating surface for regulating the protrusion ofthe plunger when it contacts with the second guide portion.

The second type of the actuator according to the present inventioncomprises a drive motor, a rotary member to be rotated clockwise andcounter-clockwise by the drive motor, and a plunger for reciprocating inits axial direction, a portion of which protrudes outside the actuator.A cylindrical supporting member is held in the rotary member, and iscapable of receiving the plunger. The supporting member has a first andsecond guide portions formed on its inner circumference. The actuatorfurther comprises a leading member fixed on the plunger. The leadingmember includes a first spiral guide surface for guiding the first guideportion therealong to move the plunger in a direction to retract it, asecond spiral guide surface for guiding the second guide portiontherealong to move the plunger in a direction to protrude it, a firstposition regulating surface for regulating the retraction of the plungerwhen it contacts with the second guide portion, and a second positionregulating surface for regulating the protrusion of the plunger when itcontacts with the first guide portion.

The third type of the actuator according to the present inventioncomprises a casing, a drive motor, and a plunger for reciprocating inits axial direction, a portion of which protrudes outside the actuator.A rotary member is rotated clockwise and counter-clockwise by the drivemotor, and includes a support sleeve into which the plunger is inserted.The support sleeve has a first and second movement guiding portionsformed on its inner circumference. A spiral leading member is fixed onthe plunger. The leading member includes a first and second spiral guidesurfaces capable of contacting with the first and second movementguiding portions, respectively, a first regulation surface formed at afirst tip end of the leading member, for contacting with the firstmovement guiding portion to regulate the rotation of the rotary member,and a second regulation surface formed at a second tip end of theleading member, for contacting with the second movement guiding portionto regulate the rotation of the rotary member. The first and secondmovement guiding portions are disposed on an inner circumference of thesupport sleeve, in such a manner that the second movement guidingportion has no interference with the second tip end of the leadingmember even when the plunger reciprocates with the first movementguiding portion being in contact with the first regulation surface ofthe leading member, and that the first movement guiding portion has nointerference with the first tip end of the leading member even when theplunger reciprocates with the second movement guiding portion being incontact with the second regulation surface of the leading member.

The fourth type of the actuator according to the present inventioncomprises a casing, a drive motor, and a cylindrical plunger forreciprocating in its axial direction, a portion of which protrudesoutside the actuator. A rotary member is rotated clockwise andcounter-clockwise by the drive motor, a portion of which is insertedinto the cylindrical plunger. The rotary member has a first and secondmovement guiding portions formed thereon. A spiral leading member isfixed on an inner circumference of the cylindrical plunger. The leadingmember includes a first and second spiral guide surfaces capable ofcontacting with the first and second movement guiding portions,respectively, a first regulation surface formed at a first tip end ofthe leading member, for contacting with the first movement guidingportion to regulate the rotation of the rotary member, and a secondregulation surface formed at a second tip end of the leading member, forcontacting with the second movement guiding portion to regulate therotation of the rotary member. The first and second movement guidingportions are arranged on an outer circumference of the rotary member, insuch a manner that the second movement guiding portion has nointerference with the second tip end of the leading member even when theplunger reciprocates with the first movement guiding portion being incontact with the first regulation surface of the leading member, andthat the first movement guiding portion has no interference with thefirst tip end of the leading member even when the plunger reciprocateswith the second movement guiding portion being in contact with thesecond regulation surface of the leading member.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel areset forth particularly in the appended claims. The invention, togetherwith the objects and advantages thereof, may best be understood byreference to the following description of the presently preferredembodiments together with the accompanying drawings.

FIG. 1 is a schematic diagram showing an electric actuator and a lockingdevice which are mounted in a door of a vehicle; and

FIG. 2 is a block diagram of a circuit for operating the door lockingdevice.

FIGS. 3 to 10 shows a first embodiment of the present invention,wherein:

FIG. 3 is a longitudinal section of an electric actuator shown togetherwith a locking device;

FIG. 4 is a diagram illustrating the engagement between a plunger and aguiding member when the guiding member makes a clockwise rotation aroundthe plunger;

FIG. 5 is a diagram illustrating the regulation of the plunger'smovement by the guide pin's contact with the guiding member;

FIG. 6 is a diagram illustrating the plunger's movement out of theactuator by the counter-clockwise rotation of the guiding member;

FIG. 7 is a front elevation showing the state in which the guidingmember is fitted in a rotary gear;

FIG. 8 is a front elevation of the guiding member;

FIG. 9 is a longitudinal section of the plunger; and

FIG. 10 is a front elevation of the guide pin of FIG. 9,

FIGS. 11 to 18 shows a second embodiment of the present invention,wherein:

FIG. 11 is a longitudinal section showing an electric actuator;

FIG. 12 is a diagram showing a plunger and a guiding member of FIG. 11and illustrates how the intrusion of the plunger is regulated by thecontact of a guide pin with a regulating surface of the guiding member;

FIG. 13 is a diagram showing the plunger and the guiding member of FIG.11 and illustrates how the plunger is protruded by a clockwise rotationof the guiding member;

FIG. 14 is a diagram showing the plunger and the guiding member of FIG.11 and illustrates how the protrusion of the plunger is regulated by thecontact of the guide pin with an another regulating surface of theguiding member;

FIG. 15 is a diagram showing the plunger and the guiding member of FIG.11 and illustrates how the plunger is intruded by a counter-clockwiserotation of the guiding member;

FIG. 16 is a diagram showing the guiding member; and

FIG. 17 is a diagram showing a rotary shaft having the guiding memberfitted thereon;

FIG. 18 is a front elevation showing the plunger.

FIGS. 19 to 25 shows a third embodiment of the present invention,wherein:

FIG. 19 is a longitudinal section showing an electric actuator;

FIG. 20 is a front elevation showing a supporting member for a rotarygear shown in FIG. 19;

FIG. 21 shows how the intrusion of a plunger is regulated by the contactof a guide pin with a regulating surface;

FIG. 22 shows how the plunger is protruded by a counter-clockwiserotation of the supporting member together with the guide pin;

FIG. 23 shows how the protrusion of the plunger is regulated by thecontact of the guide pin with an another regulating surface;

FIG. 24 shows how the plunger is intruded by a clockwise rotation of thesupporting meter together with the guide pin; and

FIG. 25 is a front elevation showing the guiding meter fitted on theplunger.

FIGS. 26 to 35 shows a fourth embodiment of the present invention,wherein:

FIG. 26 is a diagram showing the inside of an electric actuator;

FIG. 27 is a diagram showing how an enlarged slit is formed of twoslits;

FIG. 28 is a diagram showing the state in which the plunger is slightlymoved upward from the lowermost position;

FIG. 29 is a diagram showing the state in which the plunger is disposedin the uppermost position;

FIG. 30 is a diagram showing the state in which the plunger is slightlymoved downward from the uppermost position;

FIG. 31 is a front elevation showing the positional relationship betweena guide pin and the guiding member contacting with a lower guide pin;

FIG. 32 is a front elevation showing the positional relationship betweenthe guide pin and the guiding member slightly apart from the lower guidepin;

FIG. 33 is a front elevation showing the positional relationship betweenthe guide pin and the guiding member;

FIG. 34 is a perspective section showing the inside of a rotary gear andsupporting sleeves integrated with the gear; and

FIG. 35 is an expansion showing the inner circumferences of thesupporting sleeves shown in FIG. 34.

FIGS. 36 to 41 shows a fifth embodiment of the present invention,wherein:

FIG. 36 is a diagram showing the inside of an electric actuator;

FIG. 37 is a partially exploded perspective view showing a structure forregulating the vertical movements of the plunger;

FIG. 38 is a diagram showing the state in which the plunger is slightlymoved upward from the lowermost position;

FIG. 39 is a diagram showing the state in which the plunger is disposedin the uppermost position;

FIG. 40 is a diagram showing the state in which the plunger is slightlymoved downward from the uppermost position; and

FIG. 41 is a front elevation showing the construction of a rotary gearand a rotary shaft.

FIGS. 42 to 44 shows a sixth embodiment of the present invention,wherein:

FIG. 42 is a longitudinal section showing an electric actuator; FIG. 43is a partially cut-away perspective view showing the engagement betweena guide groove formed in the plunger and a guide pin formed on a rotarygear;

FIG. 44 is a front elevation showing the plunger;

FIG. 45 is a front elevation showing the guide pin formed on the innercircumference of the rotary gear;

FIG. 46 is a diagram showing the plunger which is disposed lowermostposition;

FIG. 47 is a diagram showing the plunger which is disposed in theuppermost position; and

FIG. 48 is a perspective view showing an another example of the plunger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in the following in connectionwith its first to sixth embodiments.

First Embodiment

With reference to FIGS. 3 to 10, the first embodiment will be describedin connection with an electric actuator for actuating a vehicular doorlocking device. As shown in FIG. 3, the electric actuator 1 includes abox shaped casing 2 formed of a resin. A bed 3, formed on the bottom ofthe casing 2, supports a drive motor 5 having a drive shaft 4 extendingupward therefrom. The drive shaft 4 attaches to a pinion 6 made ofresin, at the drive shaft's leading edge.

At the righthand side of the bed 3, a support wall 7 extends from theinner side of the casing 2, and is integrated with a sleeve portion 8extending upward from the support wall 7. The lower end of a plunger 9is slidably received in the sleeve portion 8, to allow for its up anddown vertical movement relative to the actuator 1. The plunger 9 has aleading end extending outside the actuator 1 through a bore 10 formed inthe upper portion of the casing 2.

The leading end of the plunger 9 is connected, via a connecting pin 11,to the leading end of a lever 12 made of a resin. This lever 12 has itsbase end connected to a locking device 14 by means of a pivot 13. As theplunger 9 is actuated to extend and retract from the upper face of thecasing 2, the lever 12 pivots on the pivot 13.

When the lever 12 is located at a position above a horizontal line Lextending through the pivot 13, the locking device 14 takes an unlockstate, in which the door 101 can be freely opened by the manipulation ofthe door handle 103 as shown in FIG. 1. Alternatively, when the lever 12is located at a position below the horizontal line L, the locking device14 takes a lock state, in which the door 100 cannot be opened even ifthe door handle 103 is manipulated.

With the upward movement of the lever 12 across the horizontal line L,the plunger 9 and the lever 12 are forcibly moved to the uppermostposition, as indicated by solid lines in FIG. 3, by the action of aspring (not shown) disposed in the locking device 14. Then, this lockingdevice 14 comes into the unlock state in which the door 101 can beopened by the manipulation of the door handle 103. With the downwardmovement of the lever 12 beneath the horizontal line L, on the otherhand, the plunger 9 and the lever 12 are forcibly moved to theirlowermost position, as indicated by double-dotted lines, by the actionof the spring in the locking device 14. Then, this locking device 14comes into the lock state, in which the door 101 is prevented from beingopened by the manipulation of the door handle 103.

The lever 12 is connected via a rod 25 to a knob 26 (similar to the knob106 in FIG. 1). Manual up or down manipulation of the knob 26 causes thelocking device 14 to take the lock or unlock state.

A first and second metal guide pins 15 and 16, as a first and secondguide members, fit into the outer circumferential surface of the plunger9, as shown in FIG. 9. These individual guide pins 15 and 16 areelliptically formed, as shown in FIG. 10, to have arcuatecontact-sliding portions 17a and 17b at their upper and lower mostportions as well as straight contact surfaces 18a and 18b at their rightand left-hand portions.

As shown in FIG. 3, the pinion 6 is engaged with a rotary gear 19 madeof a resin. A guiding member 20, made of a resin, is fixed on the centerportion of the rotary gear 19, and is formed into a generallycylindrical shape. The plunger 9 is inserted into the guiding member 20.

As shown in FIG. 8, the guiding member 20 has a spiral first guidesurface 21a formed on a portion of its upper end portion, and a spiralsecond guide surface 21b formed on a portion of its lower end portion.The first guide surface 21a couples with a first flat surface 22a and afirst position regulating surface 23a, which are formed on the guidingmember 20. The second guide surface 21b couples with a second flatsurface 22b and a second position regulating surface 23b, which areformed on the guiding member 20.

When the contact-sliding portion 17a of the lower guide pin 16 of theplunger 9 comes into contact with the flat surface 22b and when thecontact surface 18a of the guide pin 16 comes into contact with theposition regulating surface 23b, as shown in FIG. 3, the protrusion ofthe plunger 9 outside the casing 2 is regulated. At this time, a space Sis formed between the contact-sliding portion 17b of the upper guide pin15 and the guiding member 20, and allows an erection tolerance inassembling the actuator.

With the arrangement as shown in FIG. 3, when the rotary gear 19 and theguiding member 20 are rotated clockwise by the drive motor 5, thecontact-sliding portion 17a of the guide pin 16 slides through the flatface 22b along the guide surface 21b. Then, the plunger 9 is retractedinto the casing 2. In the case where the lever 12 is not located belowthe horizontal line L, the guide pin 15 is away from the guiding member20, due to the space S. When the lever 12 is located below thehorizontal line L, the plunger 9 is urged downward by the action of thespring in the locking device 14 so that the contact-sliding portion 17bof the upper guide pin 15 can come into contact with the upper end ofthe guiding member 20 to slide on the surface of the guiding member 20.Then, the lower guide pin 16 leaves the lower end of the guiding member20 to establish the space S therebetween.

When the contact surface 18b of the upper guide pin 15 comes intocontact with the first position regulating face 23a of the guidingmember 20, as shown in FIG. 5, not only the retraction of the plunger 9into the casing 2 but also the rotation of the rotary gear 19 isregulated so that the drive of the motor 5 is interrupted. Consequently,the plunger 9 comes into the casing 2 so that the lever 12 is located atthe position as indicated by the double-dotted lines in FIG. 3. At thistime, the locking mechanism in the locking device 14 comes into the lockstate, in which the door 101 cannot be opened by the manipulation of thedoor handle 103.

With the arrangement as shown in FIG. 5, when the rotary gear 19 and theguiding member 20 are rotated counter-clockwise by the drive motor 5,the contact-sliding portion 17b of the upper guide pin 15 slides throughthe flat surface 22a along the guide surface 21a, as shown in FIG. 6.Then, the plunger 9 is moved upward out of the casing 2. In case thelever 12 is not located above the horizontal line L, the lower guide pin16 is away from the guiding member 20 due to the space S. When the lever12 is located above the horizontal line L, the plunger 9 is urged upwardby the action of the spring in the locking device 14 so that thecontact-sliding portion 17a of the lower guide pin 16 can come intocontact with the lower end of the guiding member 20 to slide on thesurface of the guiding member 20. Then, the upper guide pin 15 leavesthe upper end of the guiding member 20 to form the space S therebetween.

When the contact surface 18a of the lower guide pin 16 comes intocontact with the second position regulating surface 23b of the guidingmember 20, as shown in FIG. 3, not only the movement of the plunger 9but also the rotation of the rotary gear 19 is regulated so that thedrive of the motor 5 is interrupted. Thus, the plunger 9 is protrudedfrom the casing 2 so that the lever 12 is located at the position asshown by the solid lines. At this time, the locking mechanism in thelocking device 14 comes into the unlock state, in which the door 101 canbe opened by the manipulation of the door handle 103.

Also by manual manipulation of the knob 26 provided in the inner wall ofthe door 101, the plunger 9 can be vertically moved. In other words, thelocking device 14 can be set in the lock or unlock state at any time bya passenger of the vehicle. Also in this case, the guiding member 20 hasno interference with the guide pins 15 and 16 of the plunger 9 to allowthe knob 26 to be manually operated.

Next, the operations of the electric actuator according to thisembodiment will be described. When the lever 12 is located above thehorizontal line L, as shown in FIG. 3, the plunger 9 is urged upward bythe action of the spring in the locking device 14. At this time, thecontact-sliding portion 17a of the lower guide pin 16 is in contact withthe flat surface 22b of the guiding member 20, and the contact surface18a of the guide pin 16 is in contact with the second positionregulating surface 23b of the guiding member 20. The locking device 14is in the unlock state, in which the door 101 can be opened by themanipulation of the door handle 103.

With the arrangement as shown in FIG. 3, when the rotary gear 19 and theguiding member 20 are rotated clockwise by the drive motor 5, thecontact-sliding portion 17a of the lower guide pin 16 slides through theflat surface 22b along the guide surface 21b, as shown in FIG. 4. Inaccordance with these rotations, the plunger 9 comes into the casing 2.The upper guide pin 15 will not come into contact with the upper surfaceof the guiding member 20 till the lever 12 is brought across thehorizontal line L to the lowermost position. When the lever 12 islocated below the horizontal line L, the plunger 9 urged downward by theaction of the spring in the locking device 14. Then, the contact-slidingportion 17b of the upper guide pin 15 comes into contact with the uppersurface of the guiding member 20 to form the space S between the lowerguide pin 16 and the lower surface of the guiding member 20.

As the rotary gear 19 and the guiding member 20 further rotateclockwise, the contact-sliding portion 17b of the upper guide pin 15slide on the flat surface 22a, until the contact surface 18b of theguide pin 15 comes into contact with the first position regulatingsurface 23a, as shown in FIG. 5. At this time, the retraction of theplunger 9 into the casing 2 is inhibited to regulate the rotation of therotary gear 19. Consequently, the drive of the motor 5 is interrupted.Thus, the lever 12 is located at the position as indicated by thedouble-dotted lines in FIG. 3, so that the locking mechanism of thelocking device 14 is brought into the lock state, in which the door 101cannot be opened by the manipulation of the door handle 103.

With the arrangement as shown in FIG. 5, when the rotary gear 19 and theguiding member 20 are rotated counterclockwise, the contact-slidingportion 17b of the upper guide pin 15 slides through the flat surface22a along the guide surface 21a, as shown in FIG. 6. In accordance withthese rotations, the plunger 9 is protruded outside the casing 2.Moreover, the lower guide pin 16 does not come into contact with thelower surface of the guiding member 20 so long as the lever 12 does notgo over the horizontal line L to the uppermost position. When the lever12 is located above the horizontal line L, the plunger 9 is urged upwardby the action of the spring in the locking device 14. Then, thecontact-sliding portion 17a of the lower guide pin 16 comes into contactwith the lower surface of the guiding member 20, thus forming the spaceS between the upper guide pin 15 and the guiding member 20.

When the rotary gear 19 and the guiding member 20 are further rotatedcounter-clockwise, the contact-sliding portion 17a of the lower guidepin 16 slides on the flat surface 22b, and the contact surface 18a ofthe guide pin 16 comes into contact with the second position regulatingsurface 23b of the guiding member 20, as shown in FIG. 3. At this time,the protrusion of the plunger 9 from the casing 2 is inhibited toregulate the rotation of the rotary gear 19. Consequently, the drive ofthe motor 5 is interrupted. Thus, the lever 12 is located at theposition as indicated by the solid lines, so that the locking mechanismof the locking device 14 comes into the unlock state, in which the door101 can be opened by the manipulation of the door handle 103.

In this embodiment, when the rotary gear 19 and the guiding member 20are rotated clockwise or counter-clockwise, only one of the guide pins15 and 16 comes into contact with the guiding member 20 or slides on theguiding member 20. Here, the upper guide pin 15 acts as what regulatesthe retraction of the plunger 9, whereas the lower guide pin 16 acts aswhat regulates the protrusion of the plunger 9. Accordingly, the load tobe borne by one guide pin can be reduced to approximately one half ofthat of pins of conventional actuators, so that lifetimes of theindividual guide pins 15 and 16 are at least two times as long as thoseof pins of the conventional actuators. Thus, the electric actuator ofthis embodiment is superior in durability to the conventional electricactuators.

Since the guide pins 15 and 16 are elliptically formed, they come intoline-contact with the upper or lower surface of the guiding member 20.This line-contact smoothens the sliding motions of the guide pins 15 and16 with respect to the guiding member 20. In addition, when the guidepins 15 and 16 come into contact with the first position regulatingsurface 23a or the second position regulating surface 23b of the guidingmember 20, their contact surfaces 18a and 18b make facial contact (i.e.,face to face contact) with the position regulating surface 23a or 23b todamp the impact upon the guide pins 15 and 16.

According to this first embodiment, the component for directlysupporting the rotary gear 19 can be omitted. This simplifies theconstruction of the electric actuator 1.

In the case where the electric actuator 1 and the locking device 14coupled together are to be assembled on the door, the assembling isgenerally accomplished such that the locking device 14 is in the unlockstate whereas the plunger 9 is protruded outside the actuator 1. Supposethat an electric actuator is designed without any space S between theupper guide pin 15 and the guiding member 20. If, in this case, theplunger 9 is mounted below a predetermined position in the actuator dueto an assembly error, this will cause the upper guide pin 15 tointerfere with the upper end portion of the guiding member 20, blockingthe rotations of the rotary gear 19 and the guiding member 20.

According to the first embodiment, however, the space S as shown in FIG.3 inhibits the mutual interference between the upper guide pin 15 andthe upper end portion of the guiding member 20, even if the plunger 9 isattached to a position slightly below the predetermined position. As aresult, this design can reliably prevent the electric actuator 1 frombecoming inoperative due to the assembly error.

In this first embodiment, the rotary gear 19 may be integrated with theguiding member 20 to form a single member. In order to reduce the weightof the electric actuator 1 in this embodiment, the casing 2, pinion 6,plunger 9, rotary gear 19 and guiding member 20 are made of resins. Incontrast, they may be made of metals, if necessary. Moreover, theprotrusion or intrusion of the plunger 9 may be adjusted by adjustingthe lead angles of the guide surfaces 21a and 21b which are formed onthe guiding member 20.

Second Embodiment

A second embodiment according to the present invention will be describedwith reference to FIGS. 11 to 18. The parts common to those of theforegoing first embodiment are designated at the identical referencenumerals, and their detailed description will be omitted.

As shown in FIG. 11, a casing 2 is provided with a support 31 formed onits inner wall. A drive motor 5 is fixed on the support 31, and has itsdrive shaft 4 directed downward. A resinous pinion is fixed on the driveshaft 4. In the casing 2, a resinous rotary shaft 32 is rotatablysupported by bearing portions 33a and 33b formed on the upper and lowerportions of the casing 2. With the lower end of the rotary shaft 32,there is integrally formed the resinous rotary gear 19, which is engagedwith the pinion 6.

A planar shaped plunger 9, made of a resin, is provided at the righthandside of the rotary shaft 32, and has a leading end protruding outsidethrough the bore of the casing 2. The plunger 9 is coupled with thelocking device 14 via the lever 12, like the foregoing first embodiment.

As shown in FIG. 18, the plunger 9 has a pair of guide pins 15 and 16formed on its side to face the rotary shaft 32. These guide pins 15 and16 are elliptically formed, and has arcuate contact-sliding portions 17aand 17b formed at their upper and lower portions and flat contactsurfaces 18a and 18b formed at their right and lefthand sides.

The rotary shaft 32 has the guiding member 20 formed integrallytherewith at its center. This guiding member 20 has a spiral first guidesurface 21a formed on its upper surface and a spiral second guidesurface 21b formed on its lower surface. The first guide surface 21acouples with a first flat surface 22a and a first position regulatingsurface 23a, and the second guide surface 21b couples with a first flatsurface 22b and a second position regulating surface 23b.

When the contact-sliding portion 17b of the upper guide pin 15 comesinto contact with the first flat surface 22a and when the contactsurface 18b of the guide pin 15 comes into contact with the firstposition regulating surface 23a, the retraction of the plunger 9 intothe casing 2 is regulated. At this time, the space S is formed betweenthe contact-sliding portion 17a of the lower guide pin 16 and the upperend of the guiding member 20, and allows erection tolerance inassembling the actuator.

In the case where the contact surface 18b of the upper guide pin 15 isin contact with the first position regulating surface 23a and where thecontact-sliding portion 17b of the guide pin 15 is in contact with thefirst flat surface 22a, as shown in FIGS. 11 and 12, the plunger 9 isretracted into the casing 2. At this time, the locking device 14 is inthe lock state, in which the door 101 cannot be opened by themanipulation of the door handle.

When the rotary gear 19, the rotary shaft 32 and the guiding member 20are rotated clockwise by the drive of the motor 5, the contact-slidingportion 17b of the upper guide pin 15 slides via the flat surface 22aalong the guide surface 21a, as shown in FIG. 13. As the guiding member20 rotates, the plunger 9 protrudes out of the casing 2. As long as thelever 12 is not above the horizontal line L, the lower guide pin 16 doesnot come into contact with the guiding member 20 but is spaced from themember 20 while keeping the predetermined space S therebetween.

When the lever 12 is located above the horizontal line L, the plunger 9is urged upward by the action of the spring (not shown) in the lockingdevice 14. Then, the upper guide pin 15 is spaced from the guidingmember 20 by the gap of the space S, but the lower guide pin 16 is incontact with the guiding member 20.

When the guiding member 20 is further rotated clockwise, thecontact-sliding portion 17a of the lower guide pin 16 comes into contactwith the flat surface 22b, as shown in FIG. 14, so that the contactsurface 18a comes into contact with the second position regulatingsurface 23b. Then, not only the protrusion of the plunger 9 from thecasing 2 but also the rotation of the rotary shaft 32 are regulated.Thus, the lever 12 is located at the uppermost position as indicated bythe double-dotted lines in FIG. 11. Consequently, the locking device 14comes into the unlock state, and the drive of the motor 5 isinterrupted.

With the arrangement as shown in FIG. 14, when the rotary gear 19, therotary shaft 32 and the guiding member 20 are rotated counter-clockwise,the contact-sliding portion 17a of the lower guide pin 16 slides throughthe flat surface 22b along the guide surface 21b. As the guiding member20 rotates, the plunger 9 retracts into the casing 2. As long as thelever 12 does not go down over the horizontal line L, the upper guidepin 15 does not contact with the guiding member 20 but is spaced fromthe guiding member 20 while keeping the space S.

When the lever 12 is located below the horizontal line L, the plunger 9is urged downward by the action of the spring in the locking device 14.Then, the lower guide pin 16 is spaced from the guiding member 20 by thespace S, but the upper guide pin 15 comes into contact with the guidingmember 20.

Thereafter, when the contact-sliding portion 17b of the upper guide pin15 comes into contact with the flat surface 22a and when the contactsurface 18a of the guide pin 15 comes into contact with the firstposition regulating surface 23a, as shown in FIGS. 11 and 12, not onlythe retraction of the plunger 9 into the casing 2 but also the rotationof the rotary shaft 32 is regulated. Thus, the lever 12 is brought tothe position as indicated by the solid lines, to bring the lockingdevice 14 into the lock position. At this time, the drive of the motor 5is interrupted.

The operations of the electric actuator 1 according to the secondembodiment will be described below. With the arrangement as shown inFIGS. 11 and 12, the contact surface 18b of the upper guide pin 15 is incontact with the first position regulating surface 23a, and thecontact-sliding portion 17b is in contact with the flat surface 22a. Inthis case, the intrusion of the plunger 9 into the casing 2 is inhibitedto hold the locking device 14 in the lock state. When the rotary gear19, the rotary shaft 32 and the guiding member 20 are rotated clockwiseby the drive of the motor 5, the contact-sliding portion 17b of theupper guide pin 15 slides through the flat surface 22a along the guidesurface 21a. As the guiding member 20 rotates, the plunger 9 protrudesout of the casing 2. So long as the lever 12 does not go up over thehorizontal line L, the lower guide pin 16 is kept away contact with theguiding member 20 while being held at the space S.

When the lever 12 is located above the horizontal line L, the plunger 9is urged upward by the action of the spring in the locking device 14.Then, the upper guide pin 15 is spaced from the guiding member 20 by thespace S, but the lower guide pin 16 comes into contact with the lowerend of the guiding member 20.

When the guiding member 20 is further rotated clockwise, thecontact-sliding portion 17a of the lower guide pin 16 comes into contactwith the flat surface 22b, as shown in FIG. 14, so that the contactsurface 18a comes into contact with the second position regulatingsurface 23b. Then, not only the protrusion of the plunger 9 from thecasing 2 but also the rotation of the rotary shaft 32 is regulated tobring the lever 12 to the position as indicated by the double-dottedlines in FIG. 11. At this time, the locking device 14 comes into theunlock state, and the drive of the motor 5 is interrupted.

With the arrangement as shown in FIG. 14, when the rotary gear 19, therotary shaft 32 and the guiding member 20 are rotated counter-clockwise,the contact-sliding portion 17a of the lower guide pin 16 slides throughthe flat surface 22b along the guide surface 21b, as shown in FIG. 15.As the guiding member 20 rotates, the plunger 9 is retracted into thecasing 2. So long as the lever 12 does not go down over the horizontalline L, the upper guide pin 15 does not contact with the guiding member20, but is spaced from the member 20 by the space S. When the lever 12is located below the horizontal line L, the plunger 9 is urged downwardby the action of the spring in the locking device 14. Then, the lowerguide pin 16 is spaced by the space S from the guiding member 20, butthe upper guide pin 15 comes into contact with the guiding member 20.

Thereafter, when the contact-sliding portion 17b of the upper guide pin15 comes into contact with the flat surface 22a and when its contactsurface 18b comes into contact with the first position regulatingsurface 23a, as shown in FIGS. 11 and 12, not only the intrusion of theplunger 9 but also the rotation of the rotary shaft 32 is regulated.Thus, the lever 12 is moved to the position as indicated by the solidlines, so that the locking device 14 comes into the lock state. At thistime, the drive of the motor 5 is interrupted.

According to this embodiment, either of the upper and lower guide pins15 and 16 comes into contact with the guiding member 20 even when therotary gear 19 and the guiding member 20 rotate. As a result, the loadsto be borne by the individual guide pins 15 and 16 are reduced toapproximately one half of that of pins of conventional actuators, likethe first embodiment. This drastically elongates the lifetimes of theguide pins 15 and 16, in contrast with conventional actuators.

In this second embodiment, since the guide pins 15 and 16 are formedintegrally with the plunger 9, they can sufficiently endure the impactwhich is established when they collide against the first and secondposition regulating surfaces 23a and 23b, respectively.

Since the individual guide pins 15 and 16 are elliptically formed, likethe first embodiment, the pins 15 and 16 come into line-contact with theupper and lower surfaces of the guiding member 20, respectively. Thissmoothens the sliding motions of the pins 15 and 16 with respect to theguiding member 20. Moreover, since the collisions of the guide pins 15and 16 against the position regulating surface 23a or 23b are in facialcontact, the impacts to be received by the guide pins 15 and 16 can bedamped to some extent.

The role of the space S in this second embodiment is substantiallysimilar to that of the first embodiment. Accordingly, the actuator ofthis second embodiment can also be kept away from the inoperative statewhich might otherwise be caused by the assembly error.

Although the casing 2, pinion 6, plunger 9, guide pins 15 and 16, rotarygear 19 and guiding member 20 are made of resins in order to reduce theweight of the actuator 1 in this embodiment, their components may bemade of metals, if necessary. Moreover, the protrusion or intrusion ofthe plunger 9 may be adjusted by adjusting the lead angles of the guidesurfaces 21a and 21b formed on the guiding member 20.

Third Embodiment

A third embodiment of the present invention will be described withreference to FIGS. 19 to 25. The parts common to those of the foregoingfirst embodiment are designated at the identical reference numerals, andtheir detailed description will be omitted.

As shown in FIGS. 19 and 25, a resinous plunger 9 is formed integrallywith a resinous guiding member 20 as a leading member. This guidingmember 20 has guide surfaces 21a and 21b, flat surfaces 22a and 22b, andthe first and second position regulating surfaces 23a and 23b. The topend of the plunger 9 is connected to the locking device 14 via the lever2, like the first embodiment.

The resinous rotary gear 19 has a lower resinous support pipe 41 formedintegrally with the lower end of the gear 19. An upper resinous supportpipe 42 is fitted onto the upper end of the rotary gear 19. Moreover,these lower and upper support pipes 41 and 42 form a supporting member43. The guiding member 20 of the plunger 9 is inserted into thesupporting member 43.

As shown in FIG. 20, the lower and upper support pipes 41 and 42 areintegrally formed on their inner circumferences with upper and lowerguide pins 45 and 46 as a first and second movement guiding members. Theupper guide pin 45 has an arcuate contact-sliding portion 47a formed atits lower portion, and straight contact surfaces 48a and 48b formed onthe right and left sides of the pin 45. Likewise, the lower guide pin 46has an arcuate contact-sliding portion 47b formed at its upper portion,and straight contact surfaces 49a and 49b formed on the right and leftsides of the pin 46.

When the contact-sliding portion 47b of the lower guide pin 46 of thesupporting member 43 comes into contact with the flat surface 22b of theguiding member 20 and when the contact surface 49a of the guide pin 46comes into contact with the first position regulating surface 23a, asshown in FIG. 21, the protrusion of the plunger 9 is regulated. At thistime, the space S is formed between the contact-sliding portion 47a ofthe upper guide pin 45 and the upper end of the guiding member 20, andallows erection tolerance in assembling the actuator.

When the contact surface 49a of the guide pin 46 is in contact with thefirst position regulating surface 23a and when the contact-slidingportion 47b of the guide pin 46 is in contact with the flat surface 22b,as shown in FIGS. 19 and 21, the plunger 9 is retracted into the casing2. At this time, the level 12 is located at the position as indicated bythe solid lines. The locking device 14 is in the lock state, in whichthe door 101 cannot be opened by the manipulation of the door handle103.

When the rotary gear 19, the supporting member 43 and the guide pins 45and 46 are rotated counter-clockwise by the drive motor 5, thecontact-sliding portion 47b of the guide pin 46 slides via the flatsurface 22b along the guide surface 21b, as shown in FIG. 22. Inaccordance with these rotations, the plunger 9 is protruded from thecasing 2. So long as the lever 12 does not go up over the horizontalline L, the upper guide pin 45 does not contact with the guiding member20 but is spaced from the member 20 by the space S. When the lever 12 islocated above the horizontal line L, the plunger 9 is urged upward bythe action of the spring (not shown) in the locking device 14. Then, thelower guide pin 46 is spaced by the space S from the guiding member 20,whereas the upper guide pin 45 comes into contact with the guidingmember 20.

When the guiding member 20 is further rotated counterclockwise, thecontact-sliding portion 47a of the upper guide pin 45 comes into contactwith the flat surface 22a, and the contact surface 48a comes intocontact with the second position regulating surface 23b, as shown inFIG. 23. Then, not only the protrusion of the plunger 9 but also therotation of the rotary gear 19 is regulated. At this time, the lever 12is located at the position as indicated by the double-dotted lines, sothat the locking device 14 comes into the unlock state, in which thedoor 101 can be opened by the manipulation of the door handle 103.Incidentally, the drive of the motor 5 is then interrupted.

With the arrangement as shown in FIG. 23, when the rotary gear 19, thesupporting member 43 and the guide pins 45 and 46 are rotated clockwise,the contact-sliding portion 47a of the upper guide pin 45 slides via theflat surface 22a along the guide surface 21a, as shown in FIG. 24. Inaccordance with these rotations, the plunger 9 is retracted into thecasing 2. So long as the lever 12 does not go down over the horizontalline L, the lower guide pin 46 does not come into contact with theguiding member 20 but is spaced therefrom by the space S. When the lever12 is located below the horizontal line L, the plunger 9 is urgeddownward by the action of the spring in the locking device 14. Then, theupper guide pin 45 is spaced from the guiding member 20 by the space S,whereas the lower guide pin 46 comes into contact with the guidingmember 20.

Thereafter, when the contact-sliding portion 47b of the lower guide pin46 comes into contact with the flat surface 22b, and when the contactsurface 49a of the guide pin 46 comes into contact with the firstposition regulating surface 23a, as shown in FIGS. 19 and 21, not onlythe retraction of the plunger 9 but also the rotation of the rotary gear19 is regulated. Thus, the lever 12 moves to the position as indicatedby the double-dotted lines, so that the locking device 14 comes into theunlock state. Moreover, the drive of the motor 5 is interrupted.

The operations of the electric actuator 1 according to this embodimentwill be described below. With the arrangement as shown in FIGS. 19 and21, the contact surface 49a of the lower guide pin 46 is in contact withthe first position regulating surface 23a, and the contact-slidingportion 47b of the guide pin 46 is in contact with the flat surface 22b.In this case, the plunger 9 is retracted into the casing 2 so that thelocking device 14 takes the lock state.

When the rotary gear 19, the supporting member 43 and the guide pins 45and 46 are rotated counter-clockwise by the drive of the motor 5, thecontact-sliding portion 47b of the lower guide pin 46 slides along theguide surface 21b, as shown in FIG. 22. Then, the plunger 9 protrudesupward. So long as the lever 12 does not go up over the horizontal lineL, the upper guide pin 45 does not come into contact with the guidingmember 20 but is spaced therefrom by the space S. When the lever 12 islocated above the horizontal line L, the plunger 9 is urged upward bythe action of the spring in the locking device 14. Then, the lower guidepin 46 is spaced from the guiding member 20 by the space S whereas theupper guide pin 45 comes into contact with the guiding member 20.

When the guiding member 20 is further rotated counter-clockwise, thecontact-sliding portion 47a of the upper guide pin 45 comes into contactwith the flat surface 22a, and the contact surface 48b comes intocontact with the second position regulating surface 23b. Then, not onlythe protrusion of the plunger 9 but also the rotation of the rotary gear19 is regulated. Thus, the lever 12 is moved to the position asindicated by the double-dotted lines, so that the locking device 14comes into the unlock state. At this time, the drive of the motor 5 isinterrupted.

With the arrangement as shown in FIG. 23, when the rotary gear 19, thesupporting member 43 and the guide pins 45 and 46 are rotated clockwiseby the drive of the motor 5, the contact-sliding portion 47a of theupper guide pin 45 slides through the flat surface 22a along the guidesurface 21a, as shown in FIG. 24. In accordance with these rotations,the plunger 9 is retracted into the casing 2. So long as the lever 12does not go down over the horizontal line L, the lower guide pin 46 doesnot come into contact with the guiding member 20 but is spaced therefromby the space S. When the lever 12 is located below the horizontal lineL, the plunger 9 is urged downward by the action of the spring in thelocking device 14. Then, the upper guide pin 45 is spaced from the guidemember 20 by the space S whereas the lower guide pin 46 comes intocontact with the guiding member 20.

Thereafter, the contact-sliding portion 47b of the lower guide pin 46comes into contact with the flat surface 22b whereas the contact surface49a of the guide pin 46 comes into contact with the first positionregulating surface 23a, as shown in FIGS. 19 and 21. Then, not only theretraction of the plunger 9 but also the rotation of the rotary gear 19is regulated. Thus, the lever 12 is moved to the position as indicatedby the solid lines, so that the locking device 14 takes the lock state.At this time, the drive of the motor 5 is interrupted.

According to this third embodiment, only one of the guide pins 45 and 46contacts or slides with respect to the guiding member 20. As in thefirst and second embodiments, therefore, the loads to be borne by theindividual guide pins 45 and 46 are approximately one half as large asthat of the pins of conventional actuators. This improves the lifetimesof the guide pins 45 and 46 in contrast with those of the conventionalactuators.

Since the guide pins 45 and 46 are formed integrally with the lower andupper support pipes 41 and 42, the shock resistances of the guide pins45 and 46 can be improved in the case where the pins 45 and 46 collidewith the first and second position regulating surfaces 23a and 23b.

Since the guide pins 45 and 46 are elliptically formed, like the firstand second embodiments, they come into line-contact with the upper orlower surface of the guiding member 20. This smoothens the slidingmotions of the pins 45 and 46 with respect to the guiding member 20.Moreover, the facial contacts of the guide pins 45 and 46 with the firstand second position regulating surfaces 23a and 23b can damp the impactsto be received by the pins 45 and 46.

The role of the space S in this third embodiment is substantiallyidentical to that of the first embodiment. Accordingly, the actuator ofthis third embodiment can also be kept away from the inoperative statewhich might otherwise be caused by the assembly error.

Although the casing 2, the pinion 6, the plunger 9, the rotary gear 19,the supporting member 43, and the guide pins 45 and 46 are made ofresins in order to reduce the weight of the actuator 1, they may be madeof metals, if necessary. Moreover, the protrusion and retraction of theplunger 9 may be adjusted by adjusting the lead angles of the guidesurfaces 21a and 21b which are formed on the guiding member 20.

Fourth Embodiment

A fourth embodiment of the present invention will be described withreference to FIGS. 26 to 35. The parts common to those of the foregoingfirst to third embodiments are designated at the identical referencenumerals, and their detailed description will be omitted.

A boxy casing 2, as shown in FIG. 26, is constructed by combining tworesinous separate casing parts 50 (only one of them is shown in FIG.26). A bed 3, support wall 7, sleeve portion 8 and bore 10 are formed inthe casing 2 by combining the two casing parts 50.

As shown in FIGS. 26 and 27, a resinous plunger 9 has its upper portionprotruding upward from the upper surface of the casing 2 through thebore 10. A box-shaped stroke adjusting part 51 is provided at its upperportion of the plunger 9, and has a rectangular through hole 52penetrating the adjusting part 51. An inner top surface of the throughhole 52 serves as a first position regulating surface 53a and an innerbottom surface of the through hole 52 serves as a second positionregulating surface 53b.

Each of the separate casing parts 50 has a regulating portion 54 formedthereon integrally with the part 50 to enclose the through hole 10.These two regulating portions 54 are combined to form a regulating body55 having a square top plan shape. Each regulating portion 54 has twoslits 56 formed therein. A stroke regulating piece 57 is providedbetween the two slits 56. When the two opposed regulating portions 54are combined, as shown in FIG. 27, the paired slits 56 form two enlargedslits 58, into which the stroke adjusting part 51 should be inserted.

When the plunger 9 is moved up to bring the second position regulatingsurface 53b of the stroke adjusting part 51 into contact with the strokeregulating piece 57, its upward movement of the plunger 9 is regulated.On the other hand, when the plunger 9 is moved down to bring the firstposition regulating face 53a of the stroke adjusting part 51 intocontact with the stroke regulating piece 57, its downward movement ofthe plunger 9 is regulated.

The plunger 9 is connected, via the connecting pin 11, to the lever 12of the locking device 14. When the upward movement of the plunger 9causes the connecting pin 11 to go up over the horizontal line L, theplunger 9 is urged upward by the action of the spring (not shown)provided in the locking device 14. When the second position regulatingsurface 53b of the stroke adjusting part 51 comes into contact with thestroke regulating piece 57, the upward protrusion of the plunger 9 isinhibited. When the downward movement of the plunger 9 causes theconnecting pin 11 to go down below the horizontal line L, the plunger 9is urged downward by the action of the spring in the locking device 14.When the first position regulating surface 53a of the stroke adjustingpart 51 comes into contact with the stroke regulating piece 57, theretraction of the plunger 9 is inhibited.

The plunger 9 has a guiding member 20 formed thereon integrally with theplunger 9. The guiding member 20 is disposed within the casing 2, andserves as a leading member. This guiding member 20 is spirally formed,and has a first and second guide surfaces 21a and 21b at its respectiveupper and lower sides. The first guide surface 21a is so designed thatit is moved up as the plunger 9 is rotated clockwise. The second guidesurface 21b is so designed that it is moved down as the plunger 9 isrotated clockwise. The guiding member 20 further has a first and secondregulation surfaces 25a and 25b formed at its respective tip ends. Thesetwo regulation surfaces 25a and 25b are so arranged that they do notoverlap each other in the axial direction of the plunger 9. The guidingmember 20 has its circumferential length designed not to make a roundaround the outer circumference of the plunger 9.

In the casing 2, the plunger 9 is inserted into a resinous rotary gear19. The rotary gear 19 is equipped at its central portion with supportsleeves 60a and 60b which are formed integrally with the upper and lowersurfaces of the gear 19. These support sleeves 60a and 60b have a firstand second guide pins 61a and 6lb as movement guiding portions, whichare integrally formed on their respective inner circumferentialsurfaces.

As shown in FIG. 34, the first guide pin 61a of the upper support sleeve60a has a contact surface 62a formed on its one side portion for facialcontact with the first regulation surface 25a of the guiding member 20,and a curved contact-sliding portion 63a formed on its lower end portionfor contact with the first guide surface 21a. The second guide pin 61bof the lower support sleeve 60b has a contact surface 62b formed on itsone side portion for facial contact with the second regulation surface25b of the guiding member 20, and a curved contact-sliding portion 63bformed on its upper end portion for contact with the second guidesurface 21b.

As shown in FIG. 34, the first and second guide pins 61a and 61b arespaced from each other by a predetermined gap G along the circumferencesof the support sleeves 60a and 60b. In this embodiment, thepredetermined gap G is so set that the contact surface 62a of the firstguide pin 61a is circumferentially spaced from the first regulationsurface 25a of the guiding member 20 when the contact surface 62b of thesecond guide pin 61b comes into contact with the second regulationsurface 25b of the guiding member 20. Accordingly, the first and secondguide pins 61a and 61b are so arranged that they do not face to eachother along a common axis of the plunger 9.

With the arrangement as shown in FIG. 26, even when the rotary gear 19is rotated clockwise by the drive of the motor 5, the contact-slidingportion 63b of the second guide pin 61b is kept at the start of rotationaway from contact with the second guide surface 21b of the guidingmember 20. When the rotary gear 19 is rotated clockwise to some extent,the contact-sliding portion 63b comes into contact with the second guidesurface 21b and thereafter slides along the same. As the contact-slidingportion 63b of the second guide pin 61b slides along the second guidesurface 21b, the plunger 9 is protruded upward from the casing 2, asshown in FIG. 28. When the connecting pin 11 is moved up over thehorizontal line L, the plunger 9 is urged upward by the action of thespring in the locking device 14, as shown in FIG. 29. Then, the secondposition regulating surface 53b comes into the stroke regulating piece57 to regulate the upward movement of the plunger 9.

When the plunger 9 is moved up, the second guide surface 21b of theguiding member 20 leaves the contact-sliding portion 63b of the secondguide pin 61b. In addition, the guiding member 20 is arranged in such aposition that the contact surface 62a of the first guide pin 61a cancome into facial contact with the first regulation surface 25a of theguiding member 20. When the rotary gear 19 is further rotated clockwise,the contact surface 62a of the first guide pin 61a comes into contactwith the first regulation surface 25a of the guiding member 20 so thatthe rotation of the rotary gear 19 is regulated. At this time, theactivation of the drive motor 5 stops to interrupt the rotation of therotary gear 19.

With the arrangement as shown in FIG. 29, when the rotary gear 19 isrotated counter-clockwise, the contact-sliding portion 63a of the firstguide pin 61a is kept at the beginning of the rotation away from contactwith the first guide surface 21a of the guiding member 20. When therotary gear 19 is rotated counter-clockwise to some extent, thecontact-sliding portion 63a comes into contact with the first guidesurface 21a and slides along the same. As the contact-sliding portion63a slides along the first guide pin 61a, the plunger 9 is moved down tointrude the casing 2, as shown in FIG. 30. When the connecting pin 11 ismoved down over the horizontal line L, the plunger is pushed down by theaction of the spring in the locking device 14, as shown in FIG. 26.Then, the first position regulating surface 53a comes into contact withthe stroke regulating piece 57, thus regulating the downward movement ofthe plunger 9.

When the plunger 9 is moved down, the first guide surface 21a leaves thecontact-sliding portion 63a of the first guide pin 61a. As a result ofthe downward movement of the plunger 9, moreover, the guiding member 20is arranged in such a position that the contact surface 62b of thesecond guide pin 61b can come into facial contact with the second guidesurface 21b of the guiding member 20. When the rotary gear 19 is thenfurther rotated counter-clockwise to bring the contact surface 62b ofthe second guide pin 61b into contact with the second regulation surface25b of the guiding member 20, the rotation of the rotary gear 19 isinhibited. At this time, the drive motor 5 stops and interrupts therotation of the rotary gear 19.

The operations of the electric actuator 1 of this embodiment will bedescribed below. With the arrangement as shown in FIG. 26, the lever 12is arranged below the horizontal line L, and the plunger 9 is pulleddown by the action of the spring in the locking device 14. In this case,the first position regulating surface 53a comes into contact with thestroke regulating piece 57 to regulate the retraction of the plunger 9.Moreover, the second regulation surface 25b of the guiding member 20comes into facial contact with the contact surface 62b of the secondguide pin 61b to regulate the counter-clockwise rotation of the rotarygear 19. The locking device 14 is in the lock state, in which the door101 cannot be opened by the manipulation of the door handle 103.

When the passenger pulls up the knob 26, the plunger 9 is moved up tobring the lever 12 to the position as shown by the double-dotted lines.At this time, the first regulation surface 25a of the guiding member 20has no interference with the guide pin 61a so that the plunger 9 can bemoved up. Thus, the locking device 14 is switched from the lock state tothe unlock state by the manual manipulation of the knob 26.

As the rotary gear 19 is rotated clockwise by the drive of the motor 5,the first and second guide pins 61a and 61b are also rotated clockwise.In accordance with these rotations, the contact-sliding portion 63b ofthe second guide pin 61b slides soon along the second guide surface 21b.Then, the second guide pin 61b raises the guiding member 20 to protrudethe plunger 9 upward from the casing 2, as shown in FIG. 28.

When the connecting pin 11 is moved up over the horizontal line L, thelever 12 is moved to the position as indicated by the solid lines inFIG. 29, by the action of the spring in the locking device 14. At thistime, the second position regulating surface 53b comes into contact withthe stroke regulating piece 57 to regulate the protrusion of the plunger9. As a result of the protrusion of the plunger 9, on the other hand,the first regulation surface 25a of the guiding member 20 is movedupward, and the guiding member 20 is arranged in such a position thatthe regulation surface 25a can come into facial contact with the contactsurface 62a of the first guide pin 61a.

In a short time, the contact surface 62a of the first guide pin 61a isbrought into facial contact with the first regulation surface 25a by therotation of the rotary gear 19, to regulate the rotation of the rotarygear 19. Then, the drive of the motor 5 stops, thus interrupting therotation of the rotary gear 19. Thus, the locking device 14 comes intothe unlock state, in which the door 101 can be opened by themanipulation of the door handle 103. With the arrangement as shown inFIG. 29, when the knob 26 is pushed down, the lever 12 is moved to theposition as indicated by the solid lines in FIG. 26, to bring thelocking device 14 into the lock state. When the lever 12 is moved to theposition of the solid lines of FIG. 26 so that the plunger 9 isretracted into the casing 2, the second regulation surface 25b of theguiding member 20 has no interference with the second guide pin 61b sothat the knob 26 can be pushed down without fail.

As the rotary gear 19 is rotated counter-clockwise from the arrangementshown in FIG. 29 by the drive of the motor 5, the first and second guidepins 61a and 61b are also rotated counter-clockwise. By these rotations,the contact-sliding portion 63a of the first guide pin 61a slides soonalong the first guide surface 21a. Then, the first guide pin 61a pushesdown the guiding member 20 to retract the plunger 9 into the casing 2,as shown in FIG. 30.

When the connecting pin 11 is moved down over the horizontal line L, thelever 12 is moved to the position as indicated by the solid lines inFIG. 26, by the action of the spring in the locking device 14. At thistime, the first position regulating surface 53a comes into contact withthe stroke regulating piece 57 to regulate the retraction of the plunger9. As a result of the retraction of the plunger 9, the second regulationsurface 25b of the guiding member 20 is moved down, and the guidingmember 20 is arranged in such a position that the regulation surface 25bcan come into facial contact with the contact surface 62b of the guidepin 61b.

As the rotary gear 19 rotates, the contact surface 62b of the secondguide pin 61b comes into facial contact with the second regulationsurface 25b to regulate the rotation of the rotary gear 19. At thistime, the drive of the motor 5 stops, thus interrupting the rotation ofthe rotary gear 19. Thus, the locking device 14 comes into the lockstate, in which the door 101 cannot be opened by the manipulation of thedoor handle 103.

After the contact surface 62b of the second guide pin 61b has come intofacial contact with the second regulation surface 25b of the guidingmember 20, as shown in FIG. 31, the rotary gear 19 stops. Let it beassumed that the rotary gear 19 be slightly returned clockwise by theimpact of the facial contact between the contact surface 62b and theregulation surface 25b to separate the contact surface 62b and theregulation surface 25b slightly from each other, as shown in FIG. 32. Atthis time, the guide pin 61a is also rotated clockwise to an extentcorresponding to the slight separation.

Since the gap G is retained in advance between the first guide pin 61aand the second guide pin 61b, however, the upper guide pin 61a would notcollide against that tip portion of the guiding member 20 having thefirst regulation surface 25a even if the plunger 9 were pulled up withthe arrangement as shown in FIG. 32. This discussion likewise applies tothe case in which the plunger 9 is pushed down where the contact surface62a of the first guide pin 61a slightly leaves the first regulationsurface 25a of the guiding member 20. In that case, too, the secondguide pin 61b will not collide against that tip portion of the guidingmember 20 having the second regulation surface 25b. Consequently,according to this embodiment, the plunger 9 can be pulled up or pusheddown without fail by the manual manipulation of the knob 26 so that thelocking device 14 can be manually switched between the lock state andthe unlock state.

FIG. 35 is an expansion showing the support sleeves 60a and 60b. If thelower guide pin 61 is arranged in the position as indicated by thedouble-dotted lines, a hatched area A1 is formed between the upper andlower guide pins 61a and 61b. In case such support sleeves 60a and 60bare molded, the upper guide pin 61a, the lower guide pin 61b and theblock filling the area A1 have to be once formed, and then the block ofthe area A1 has to be cut away. In other words, the internal shape ofthe support sleeves cannot be formed by a single molding step in casethe upper and lower guide pins 61a and 61b are opposed to each other.

In this embodiment, however, the lower guide pin 61b is located on theinner circumference of the sleeve with a displacement of the gap G fromthe upper guide pin 61a. This makes it possible to prepare such a moldas can part the sleeves from the inside after the sleeves have beenmolded. As a result, the two guide pins 61a and 61b can be integrallyformed on the inner circumference of the support sleeves 60a and 60bsimultaneously with the process for molding the support sleeves 60a and60b. Additionally, the guiding member 20 is designed to make anincomplete surrounding around the plunger 9, so that the plunger 9 canbe produced by a single molding process while forming the guiding member20 integrally.

According to this fourth embodiment, only one of the first and secondguide pin 61a and 61b contacts with or slides on the guiding member 20.Like the first to third embodiments, therefore, the loads to be borne bythe individual guide pins 61a and 61b are approximately one half aslarge as that of the pins of conventional actuators, so that thelifetimes of the guide pins 61a and 61b can be more elongated than thoseof the pins of conventional actuators.

Since the guide pins 61a and 61b are formed integrally with the supportsleeves 60a and 60b, the shock resistance of the pins 61a and 61b isimproved in the case where the guide pins 61a and 61b come intocollision against the regulation surfaces 25a and 25b.

Since the individual contact-sliding portions 63a and 63b of the guidepins 61a and 61b to contact with the first and second guide surfaces 21aand 21b are curved, the guide pins 61a and 61b come into line-contactwith the first and second guide surfaces 21a and 21b. This smoothens thesliding motions of the guide pins on the guide surfaces.

Moreover, since the guide pins 61a and 61b come into facial contact withthe regulation surfaces 25a and 25b of the guiding member 20, the shocksto be received by the guide pins 61a and 61b are dispersed all over theassociated contacting surfaces. This prevents the guide pins 61a and 61bfrom being partially worn, resulting in the improvement of thedurability of the guide pins 61a and 61b.

While one guide pin (61a or 61b) is in contact with its associatedregulation surface (25a or 25b), the other guide pin is spaded from itsassociated guide surface (21a or 21b). When the rotary gear 19 isrotated to some extent, that other guide pin comes into contact with itsassociated guide surface. Accordingly, even if the plunger 9 isassembled with the lever 12 with a slight displacement from apredetermined position, no mutual interference occurs between the guidepins and the guiding member. Thus, the actuator of this embodiment canbe reliably prevented from the inoperative state which might otherwisebe caused by the assembly error.

Although the casing 2, the pinion 6, the plunger 9, the guiding member20, the rotary gear 19, the support sleeves 60a and 60b and the guidepins 61a and 61b are made of resins in order to reduce the weight of theactuator 1, they may be made of metals, if necessary. The guide pins 61aand 61b may be produced separate from the support sleeves 60a and 60b.The guiding member 20 may also be produced separate from the plunger 9.

Fifth Embodiment

A fifth embodiment, which is a modification of the fourth embodiment,will be described with reference to FIGS. 36 to 41. As shown in FIG. 36,a resinous plunger 9 is hollowly formed, and has a guiding member 20 asa leading member formed on its lower inner wall integrally with theplunger 9. A resinous rotary shaft 70 is formed integrally with therotary gear 19, at the center of the gear 19. The rotary shaft 70 hasits top end rotatably received by the stroke regulating piece 57 and itsbottom end rotatably received by a small sleeve portion 8 formed on asupport wall 7. As shown in FIGS. 36 and 41, a first and second guidepins 61a and 61b as a first and second movement guiding members areformed integrally with the rotary shaft 70, on the outer circumferenceof the shaft, like the fourth embodiment.

With the arrangement as shown in FIG. 36, the locking device 14 is inthe lock state, in which the door 101 cannot be opened by themanipulation of the door handle 103. When the knob 26 is pulled up, thelever 12 is moved to the position as indicated by the double-dottedlines, and the plunger 9 is moved upward. At this time, the lockingdevice 14 is in the unlock state, in which the door 101 can be opened bythe manipulation of the door handle 103.

With the arrangement as shown in FIG. 36, even when the rotary gear 19and the rotary shaft 70 are rotated clockwise by the drive of the motor5, the contact-sliding portion 63b of the lower guide pin 61b is kept atan initial stage away from contact with the second guide surface 21b ofthe guiding member 20. When the rotary shaft 70 is rotated to someextent, the lower guide pin 61b slides along the second guide surface21b. In accordance with this sliding, the lower guide pin 61b pushes thesecond guide surface 21b to move the plunger 9 upward, as shown in FIG.38.

When the connecting pin 11 is located above the horizontal line L, theplunger 9 is raised up to the uppermost position shown in FIG. 39 by theaction of the spring (not shown) in the locking device 14. Then, thesecond position regulating surface 53b formed on the plunger 9 comesinto contact with the stroke regulating piece 57 to regulate theprotrusion of the plunger 9. When the rotary shaft 70 is further rotatedclockwise, the contact surface 62a of the upper guide pin 61a comes intocontact with the first regulation surface 25a, thereby regulating therotation of the rotary shaft 70. At this time, the drive of the motor 5stops to interrupt the rotation of the rotary shaft 70. When the knob 26is pushed down by a passenger, the plunger 9 is moved down into thecasing 2, so that the lever 12 is moved to the position as indicated bythe solid lines in FIG. 36. At this time, the locking device 14 takesthe lock state.

With the arrangement as shown in FIG. 36, even when the rotary gear 19and the rotary shaft 70 are rotated counter-clockwise, thecontact-sliding portion 63a of the upper guide pin 61a is kept at aninitial stage away from contact with the first guide surface 21a. Whenthe rotary shaft 70 is rotated to some extent, the upper guide pin 61aslides along the first guide surface 21a. In accordance with thissliding, the upper guide pin 61a pushes the first guide surface 21a tomove the plunger 9 downward, as shown in FIG. 40.

When the connecting pin 11 is moved down over the horizontal line L, theplunger 9 is pulled down by the spring in the locking device 14. Asshown in FIG. 36, the first position regulating surface 53a formed onthe plunger 9 comes into contact with the stroke regulating piece 57 toregulate the retraction of the plunger 9. When the rotary shaft 70 isfurther rotated counter-clockwise, the second regulation surface 25b ofthe guiding member 20 comes into contact with the contact surface 62b ofthe lower guide pin 61b, regulating the rotation of the rotary shaft 70.At this time, the drive of the motor 5 stops to interrupt the rotationof the rotary shaft 70. When the knob 26 is pulled up by the passenger,the plunger 9 is moved up so that the lever 12 is moved to the positionas indicated by the double-dotted lines in FIG. 36. At this time, thelocking device 14 comes into the unlock state.

The two guide pins 61a and 61b are formed, as in the fourth embodiment,on the rotary shaft 70 at a circumferential spacing of the gap G. As aresult, even when the guide pin 61a or 61b is not in close contact withthe regulation surface 25a or 25b of the guiding member 20, the plunger9 can be moved up and down by the manual manipulation of the knob 26,like the fourth embodiment.

According to this embodiment, even when the rotary gear 19, the rotaryshaft 70 and the guide pins 61a and 61b are rotated, only one of theguide pins 61a and 61b comes into contact with the guiding member 20.Accordingly, the loads to be borne by the individual guide pins 61a and61b are approximately one half as large as those of the pins ofconventional actuators, so that the lifetimes of the guide pins 61a and61b can be more elongated than those of the conventional actuators.

Since the contact-sliding portions 63a and 63b of the guide pins 61a and61b are curved, the guide pins 61a and 61b come into line-contact withthe first and second guide surfaces 21a and 21b. This smoothens thesliding motions of the guide pins 21a and 21b.

Like the foregoing fourth embodiment, moreover, the actuator of thisembodiment has the advantages that the guide pins 61a and 61b are infacial contact with the regulation surfaces 25a and 25b of the guidingmember 20 and that the actuator is not made inoperative by the assemblyerror.

Although the casing 2, the pinion 6, the plunger 9, the guiding member20, the rotary gear 19, the rotary shaft 70, and the guide pins 61a and61b are made of resins in order to reduce the weight of the actuator 1,they may be made of metals, if necessary. The plunger 9 and the guidingmember 20 also be produced separate from each other.

Sixth Embodiment

A sixth embodiment of the present invention will be described withreference to FIGS. 42 to 48. The parts common to those of the foregoingfirst to fifth embodiments are designated at the identical referencenumerals, and their detailed description will be omitted.

As shown in FIG. 42, a drive motor 5 is mounted on a bed 3 of a casing 2of an electric actuator 1. A pinion 6 is fixed on a drive shaft 4 of themotor 5. A bottom end of the plunger 9 is received by a sleeve portion 8formed on the bottom wall of the casing 2 such that the plunger 9 isvertically movable. A top end of the plunger 9 is protruded upwardthrough a bore 10 formed in the upper wall of the casing 2.

The top end of the plunger 9 is connected to a distal end of the lever12, via a connecting pin 11. The lever 12 has a proximal end connectedto the locking device 14 via a pivot 13. When the plunger 9 is protrudedfrom the casing 2 so that the lever 12 goes up over the horizontal lineL extending through the pivot 13, the plunger 9 and the lever 12 aremoved to the uppermost position as indicated by the double-dotted lines,by the action of the spring (not shown) in the locking device 14. Atthis time, the locking device 14 takes the unlock state. On the otherhand, when the plunger 9 is retracted into the casing 2 so that thelever 2 goes down over the horizontal line L, the plunger 9 and thelever 12 are moved to the lowermost position as indicated by the solidlines, by the action of the spring in the locking device 14. At thistime, the locking device 14 takes the lock state.

The plunger 9 has a spiral guide groove 74 formed on its circumferentialwall, and a connecting groove 79 extending in the axial direction of theplunger 9 and connecting the upper and lower end portions of the guidegroove 74. A first regulation surface 75 is formed at the upper endportion of the guide groove 74, the upper portion serving as a firstregulation position 76. A second regulation surface 77 is formed at thelower end portion of the guide groove 74, the lower portion serving as asecond regulation position 78.

A rotary gear 80, engaged with the pinion 6, has a bore 81 formed in itscenter, for receiving the plunger 9. A guide pin 82 is formed on aninner circumference of the gear 80 integrally with the gear 80, andserves as a guide member to engage with the guide groove 74. The rotarygear 80 is supported on the plunger 9, by means of the engagement of theguide pin 82 with the guide groove 74. As shown in FIG. 45, the guidepin 82 has arcuate contact-sliding portions 83a and 83b formed on itsupper and lower portions, and straight contact surfaces 84a and 84bformed on its right and left-hand sides.

With the arrangement as shown in FIG. 47, when the rotary gear 80 isrotated clockwise by the drive of the motor 5 for a predetermined periodof time, the guide pin 82 is slid along the guide groove 74. Since theplunger 9 is urged upward by the action of the spring in the lockingdevice 14, the lower contact-sliding portion 83b of the guide pin 82 ispressed against the lower inner wall of the guide groove 74.

In accordance with the clockwise rotation of the rotary gear 80, theplunger 9 is moved down so that it is gradually retracted into thecasing 2. When the lever 12 is located below the horizontal line L bythe downward movement of the plunger 9, the upper contact-slidingportion 83a of the guide pin 82 is pressed against the upper inner wallof the guide groove 74 by the action of the spring in the locking device14. Thereafter when the contact surface 84a of the guide pin 82 comesinto contact with the first regulation surface 75 to regulate thedownward movement of the guide pin 82, as shown in FIG. 46, the rotationof the rotary gear 80 is regulated to interrupt the drive of the motor5. Then, the guide pin 82 is located in the first regulation position 76to regulate any further downward movement of the plunger 9 so that theplunger 9 is retracted into the casing 2. Moreover, the locking device14 takes the lock state.

With the arrangement as shown in FIG. 46, when the rotary gear 80 isrotated counter-clockwise by the drive of the motor 5 for apredetermined period of time, the guide pin 82 is slid along the guidegroove 74. At this time, since the plunger 9 is urged downward by theaction of the spring in the locking device 14, the upper contact-slidingportion 83a of the guide pin 82 is pressed against the upper inner wallof the guide groove 74.

In accordance with the counter-clockwise rotation of the rotary gear 80,the plunger 9 is moved up so that it is gradually protruded from thecasing 2. When the lever 12 is located above the horizontal line L, thelower contact-sliding portion 83b of the guide pin 82 is pressed againstthe lower inner wall of the guide groove 74 by the action of the springin the locking device 14. When the contact surface 84b of the guide pin82 comes into contact with the second regulation surface 77, as shown inFIG. 47, the rotation of the rotary gear 80 is regulated to interruptthe drive of the motor 5. At this time, the guide pin 82 is located inthe second regulation position 78 to regulate any further upwardmovement of the plunger 9, so that the plunger 9 is protruded out of thecasing 2. Moreover, the locking device 14 takes the unlock state.

When the plunger 9 is moved up and down with the guide pin 82 beingpositioned in the first or second regulation position 76 or 78, theguide pin 82 can be switched, via the connecting groove 79, between thefirst and second regulation positions 76 and 78. Accordingly, thelocking device 14 can be brought into the lock or unlock state, by themanual manipulation of the knob 106 for door locking. Since, in thiscase, the guide pin 82 located at the first regulation position 76 canbe moved to the second regulation position 78 via the connecting groove79, the plunger 9 can be manually protruded out of the casing 2. On theother hand, since the guide pin 82 located at the second regulationposition 78 can be moved to the first regulation position 76 via theconnecting groove 79, the plunger 9 can be manually retracted into thecasing 2.

The operations of the actuator 1 of this embodiment will be describedbelow. While the plunger 9 is retracted in the casing 2, as shown inFIG. 46, the lever 12 is located below the horizontal line L so that thelocking device 14 is in the lock state. At this time, the plunger 9 islocated at the lowermost position via the lever 12 by the action of thecoil spring in the locking device 14. Accordingly, the guide pin 82 ispositioned in the first regulation position 76, and the contact surface84a of the guide pin 82 is in contact with the first regulation surface75 whereas the contact-sliding portion 83a is in contact with the upperinner surface of the guide groove 74.

As the rotary gear 80 is rotated counter-clockwise, the guide pin 82moves along the guide groove 74. In accordance with the movement of thepin 82, the plunger 9 is moved up. When the lever 12 is located abovethe horizontal line L, the plunger 9 is pulled up by the action of thespring in the locking device 14. As a result, the lower contact-slidingportion 83b of the guide pin 82 comes into contact with the lower innersurface of the guide groove 74. When the contact surface 84b of theguide pin 82 comes into contact with the second regulation surface 77 sothat the guide pin 82 is located at the second regulation position 78,as shown in FIG. 47, the drive motor 5 stops. When the plunger 9 islocated at the uppermost position, the locking device 14 takes theunlock state.

with the arrangement as shown in FIG. 47, as the rotary gear 80 isrotated clockwise so that the guide pin 82 moves along the guide groove74, the plunger 9 moves down. When the lever 12 is located below thehorizontal line L, the plunger 9 is pulled down by the action of thespring in the locking device 14. Then, the upper contact-sliding portion83a of the guide pin 82 comes into contact with the upper inner surfaceof the guide groove 74. When the contact surface 84a of the guide pin 82comes into contact with the first regulation surface 75 so that theguide pin 82 is located at the first regulation position 76, as shown inFIG. 46, the drive motor 5 stops. Thus, the plunger 9 is located at thelowermost position, and the locking device 14 takes the lock state.

In case the knob 106 is manipulated with the guide pin 82 beingpositioned in the first regulation position 76 or the second regulationposition 78, the connecting groove 79 allows the plunger 9 to verticallymove. As a result, the locking device 14 can be controlled by the manualoperation of the knob 106.

The provision of the guide groove 74 for the plunger 9 to engage withthe guide pin 82 achieves omission of the special construction forsupporting the rotary gear 80. As a result, the electric actuator 1 canbe made compact.

Since the contact-sliding portions 83a and 83b of the guide pin 82 arearcuately formed, the sliding resistance of the guide pin 82 to theupper or lower inner surface of the guide groove 74 is reduced, thussmoothening the sliding motions of the guide pin 82 along the guidegroove 74. Moreover, the flat contact surfaces 84a and 84b, formed onthe right and left sides of the guide pin 82, damp the shocks which arecaused when the guide pin 82 contacts with the first or secondregulation surface 75 or 77.

In this embodiment, the stroke of vertical movement of the plunger 9 canbe adjusted by changing the lead angle and/or length of the guide groove74.

If the manual manipulation of the plunger 9 is not required, a spiralguide groove 74 having the first and second regulation positions 76 and78 may be merely formed on the outer circumference of the plunger 9, asshown in FIG. 48.

Although only six embodiments of the present invention have beendescribed herein, it should be apparent to those skilled in the art thatthe present invention may be embodied in many other specific formswithout departing from the spirit or scope of the invention. Therefore,the present examples and embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope of theappended claims.

What is claimed is:
 1. An actuator comprising:a casing; a drive motor acylindrical plunger for reciprocating in its axial direction, a portionof which protrudes outside the actuator; a rotary member to be rotatedclockwise and counter-clockwise by said drive motor, a portion of whichis inserted into said cylindrical plunger, said rotary member having afirst and second movement guiding portions formed thereon; and a spiralleading member fixed on an inner circumference of said cylindricalplunger, wherein said leading member includes: a first and second spiralguide surfaces capable of contacting with said first and second movementguiding portions, respectively; a first regulation surface formed at afirst tip end of the leading member, for contacting with said firstmovement guiding portion to regulate the rotation of said rotary member;and a second regulation surface formed at a second tip end of theleading member, for contacting with said second movement guiding portionto regulate the rotation of said rotary member; wherein said first andsecond movement guiding portions are arranged on an outer circumferenceof said rotary member, in such a manner that said second movementguiding portion has no interference with said second tip end of saidleading member even when said plunger reciprocates with said firstmovement guiding portion being in contact with said first regulationsurface of said leading member, and that said first movement guidingportion has no interference with said first tip end of said leadingmember even when said plunger reciprocates with said second movementguiding portion being in contact with said second regulation surface ofsaid leading member; and wherein said first movement guiding portion andsaid second movement guiding portion are arranged apart from each otherat a predetermined gap (G) along the circumference of said rotarymember.
 2. The actuator according to claim 1 further comprisingregulation means, provided in said plunger and said casing, forregulating the reciprocation of said plunger.
 3. An actuatorcomprising:a casing; a drive motor a cylindrical plunger forreciprocating in its axial direction, a portion of which protrudesoutside the actuator; a rotary member to be rotated clockwise andcounter-clockwise by said drive motor, a portion of which is insertedinto said cylindrical plunger, said rotary member having a first andsecond movement guiding portions formed thereon; anda spiral leadingmember fixed on an inner circumference of said cylindrical plunger,wherein said leading member includes: a first and second spiral guidesurfaces capable of contacting with said first and second movementguiding portions, respectively; a first regulation surface formed at afirst tip end of the leading member, for contacting with said firstmovement guiding portion to regulate the rotation of said rotary member;a second regulation surface formed at a second tip end of the leadingmember, for contacting with said second movement guiding portion toregulate the rotation of said rotary member; and regulation means,provided in said plunger and said casing, for regulating thereciprocation of said plunger; wherein said regulation means includes: astroke adjusting part (51) carried on a distal end of said plunger andhaving a first and second position regulating surfaces (53a, 53b); and astroke regulating piece (57) formed in said casing, for contacting withone of said first and second position regulating surfaces (53a, 53b) todetermine the stroke of the reciprocation of said plunger; and whereinsaid first and second movement guiding portions are arranged on an outercircumference of said rotary member, in such a manner that said secondmovement guiding portion has no interference with said second tip end ofsaid leading member even when said plunger reciprocates with said firstmovement guiding portion being in contact with said first regulationsurface of said leading member, and that said first movement guidingportion has no interference with said first tip end of said leadingmember even when said plunger reciprocates with said second movementguiding portion being in contact with said second regulation surface ofsaid leading member.
 4. An actuator comprising:a casing; a drive motor acylindrical plunger for reciprocating in its axial direction, a portionof which protrudes outside the actuator; a rotary member to be rotatedclockwise and counterclockwise by said drive motor, a portion of whichis inserted into said cylindrical plunger, said rotary member having afirst and second movement guiding portions formed thereon; anda spiralleading member fixed on an inner circumference of said cylindricalplunger, wherein said leading member includes: a first and second spiralguide surfaces capable of contacting with said first and second movementguiding portions, respectively; a first regulation surface formed at afirst tip end of the leading member, for contacting with said firstmovement guiding portion to regulate the rotation of said rotary member;and a second regulation surface formed at a second tip end of theleading member, for contacting with said second movement guiding portionto regulate the rotation of said rotary member; wherein said first andsecond movement guiding portions are arranged on an outer circumferenceof said rotary member, in such a manner that said second movementguiding portion has no interference with said second tip end of saidleading member even when said plunger reciprocates with said firstmovement guiding portion being in contact with said first regulationsurface of said leading member, and that said first movement guidingportion has no interference with said first tip end of said leadingmember even when said plunger reciprocates with said second movementguiding portion being in contact with said second regulation surface ofsaid leading member; wherein said first movement guiding portion of saidrotary member includes a contact-sliding portion for coming intoline-contact with said first spiral guide surface of said leadingmember, and a contact surface of coming into facial contact with saidfirst regulation surface of said leading member; and wherein said secondmovement guiding portion of said rotary member includes acontact-sliding portion for coming into line-contact with said secondspiral guide surface of said leading member, and a contact surface forcoming into facial contact with said second regulation surface of saidleading member.